The present invention relates generally to gas generating systems for use in inflatable occupant protection systems in motor vehicles.
Installation of inflatable occupant protection systems, generally known as “airbags,” as standard equipment in all new vehicles has intensified the search for smaller, lighter and less expensive protection systems. Accordingly, since the gas generating system used in such systems tends to be the heaviest and most expensive component, there is a need for a lighter and less expensive gas generating system.
Extensive use of metals such as steel in the structure of the gas generating system also adds to the weight of the gas generating system. In addition, gas generator housings may be formed from materials such as aluminum. These relatively lightweight materials can lose strength at abnormally high temperatures, such as those reached in a vehicle fire. At temperatures experienced in a vehicle fire, the gas generating material may autoignite and produce inflation fluid at a pressure sufficient to cause the inflator housing to lose its structural integrity due to the reduced strength of the inflator housing material. To prevent such loss of structural integrity, inflators typically include an autoignition material that will autoignite and initiate combustion of the gas generating material at a temperature below that at which the material of the housing begins to lose a significant percentage of its strength. However, the provision and positioning of this autoignition material in the gas generator adds to the component and assembly costs of the gas generating system.